A mouse is an essential input device for a computer system. By operating the mouse to click or scroll the computer screen, the user can open a document file or other work file from the computer screen in order to read documents or web pages.
Conventionally, a mouse comprises a casing, two buttons, a scroll wheel, a circuit board, a button sensor, an encoder, a controller, an optical sensor and a power-providing element. The two buttons are installed on the casing and connected with the button sensor. The scroll wheel is installed on the casing, arranged between the two buttons, and connected with the encoder. The circuit board, the button sensor, the encoder, the controller, the optical sensor and the power-providing element are disposed within the casing. Moreover, the button sensor, the encoder, the controller, the optical sensor and the power-providing element are electrically connected with the circuit board.
As mentioned above, the two buttons and the scroll wheel are fixed on the casing, and the circuit board, the button sensor, the encoder, the controller, the optical sensor and the power-providing element are disposed within the casing. However, the conventional mouse still has some drawbacks. For example, the positions of the two buttons and the scroll wheel of the conventional mouse cannot be determined according to the preference or the use habit of the user. Moreover, the conventional mouse cannot be equipped with any other expansion module.